1. Field of the Invention (Technical Field)
The present invention relates to methods and apparatuses for the production of liquid fertilizer from waste using successive extraction and accelerated bioleaching resulting in increased nitrogen content and decreased odor during production.
2. Description of Related Art
Note that where the following discussion refers to a number of publications by author(s) and year of publication, that due to recent publication dates certain publications are not to be considered as prior art vis-a-vis the present invention. Discussion of such publications herein is given for more complete background and is not to be construed as an admission that such publications are prior art for patentability determination purposes.
Organic farming was one of the fastest growing segments of U.S. agriculture during the 1990's (USDA-ERS 2002). U.S. sales of organic food products grew 20-25% annually during the past decade reaching $7 billion in 2000 (USDA-2002). Traditionally, organic farming has relied on composted organic material or rotation crops as sources of plant nutrients.
U.S. Patent Application Publication No. 2006/0172888 to Blasczyk et al., entitled “Natural Grass Fertilizer With Weed and Grub Control Activity,” issued Aug. 3, 2006, discloses a process for making a fertilizer by combining liquid steep-water obtained by steeping vegetable matter in water and subsequently straining the solid matter from the liquid. A natural fertilizer comprising steep-water and biomass is produced.
U.S. Patent Application Publication No. 2004/0172997 to Huang et al., entitled “Plant Nutrition Formulated By Recovery Filtrate From Plant Fiber Biopulp And Method Thereof,” issued Sep. 9, 2004, discloses a plant nutrition formulation and method relating to the recovery filtrate from plant biopulp that is not harmful to the environment.
U.S. Pat. No. 7,014,768 to Li et al., entitled “Process For Removal And Recovery Of Nutrients From digested Manure Or Other Organic Wastes,” issued Mar. 21, 2006, discloses a multi-step process of removing nutrients and water from organic wastes and recycling digested liquids back through the digested solids at an elevated temperature to create a biofertilizer with an elevated nitrogen content.
U.S. Pat. No. 6,299,774 to Ainsworth et al., entitled “Anaerobic Digester System,” issued Oct. 9, 2001, discloses a process that involves the anaerobic digestion of feedstocks at low to high temperatures in batch reactors to produce fertilizer.
U.S. Patent Application Publication No. 2004/0000179 to Hiraki, entitled “Method For Composting Organic Wastes,” issued Jan. 1, 2004, discloses a method for composting wastes with water and effective microorganisms (EM) at a suitable temperature to create a fertilizing compost.
The present invention comprises generating liquid fertilizer that can be applied through irrigation systems. Liquid fertilizer has several potential advantages compared to traditional composting methods. For example, liquid fertilizer is a clean plant-based fertilizer and does not have the typical problems of weed seeds, pathogens, or high sodium content. Also, liquid fertilizer is dissolved in water and is easily available for plant uptake contrary to composted material where only a fraction of the nutrient is available for plant uptake and often needs to be supplemented with mineral fertilizer. Also, liquid fertilizer can be applied to plants on a timely basis as needed. The following are examples of devices and processes that produce fertilizer.
The present invention preferably uses a plant source, anaerobically digests the plant source, and subsequently uses a sequential bioleaching process which increases the amount of nutrient extracted or leached from a fixed amount of organic plant source. The leachate is concentrated without losing the nutrient and is subsequently used as a fertilizer (preferably an organic fertilizer). The present invention uses moderate heat at an optimum temperature to enhance hydrolysis and acidification and reduces the time required to produce the nutrient-rich leachate. No pre-treatment is required to digest the plant source. The present invention is lightweight, inexpensive, and uses a successive extraction process to produce an organic fertilizer with an enhanced nitrogen content.